You should generally post these types of questions in "Discussions" -- you'll get more responses.

But, in answer to your question, there are a couple you can look at:

1) Kohler makes a smaller, deep tub that's 48 inches wide called the "Greek". I've posted a link.

2) MTI makes a 50 inch tub called the "Altantica" They also make a 48 inch square Japanese soaking tub called the "Furo 1" or the "Furo 2" Their website is very easy to navigate and is www.mtiwhirlpools.com.

That oughta get you started.

Here is a link that might be useful: kohler greek tub